Captivate 19 html video with embedded Exit button closes the whole web browser tab on click

In our Brightspace course we use html videos exported as zip files from Captivate. We then upload the zip file to Manage Files and then we unzip the file and point to the index.html in a module for a course video. Within the video, there is an embedded exit button at the end of the video that generally just exits out of the video and then we see a message saying we have completed the activity.

However, recently, a colleague working in the course noticed that all her videos are "closing" out of the entire video tab when she clicks exit in the video. Specifically, when she clicks "Exit Lesson" it closes the whole web browser tab immediately as if she had clicked the x on the web browser tab.

I am looking to find out if this is this a browser issue or a Captivate file issue? I tend to think its a browser issue because its behaving normally for me - in that it doesn't close the web browser tab. She has tried it in all the web browsers and it seems to still be happening but I can't replicate it on my end.

Has anyone run into this before?

The videos show as a web page - not a content object - which has the option to open in an external window or an embedded player. Curious if this has been an issue before for others and if so, what is the remedy?